The present invention relates to round or roll baling machines of the type disclosed in Blanshine et al. U.S. Pat. No. 4,026,205 and having a bale wrapping mechanism of the type disclosed in U.S. Pat. No. 4,253,389.
A round baling machine (baler) of the type disclosed in the patent to Blanshine et al. is pulled along a windrow, gathers the crop from the windrow and forms it into a round bale. The baler includes a chamber and a mechanism for rotating the crop material in the chamber so that it is formed into an increasingly larger roll or bale. After a full bale has been formed, a tailgate at the rear of the baler may be opened so that the bale may be ejected and fall to the ground behind the baler.
It is known to provide a wrapping mechanism for wrapping each bale with a wrapping filament or twine prior to the time it is ejected so that the bale will maintain its compactness and can be more easily handled without falling apart. The wrapping mechanism may comprise one or more arms which are moved in front of a rotating bale and carry twine which is dispensed so that it is caught up in the last couple of layers of the bale as it is formed, and then wrapped around the fully formed bale.
The prior art also teaches that the wrapping mechanism may be caused to operate automatically in response to signals from a controller to wrap each bale in a predetermined pattern. Boldenow et al. U.S. Pat. No. 4,354,429 discloses a time based controller for controlling the movement of a single twine dispensing arm, the arm being moved arcuately in front of a rotating bale to form helical wraps of twine around the bale and the arm being selectively stopped so that circular wraps of twine are formed at selected locations. During normal operation the twine dispensing arm starts from a "home" end of a bale and ends a wrapping operation at the point from which it started. However, since the controller is time based, and there are no interlocks, the controller may fail to return the twine dispensing arm to the home position. This could occur if there should be a heavy loading of the twine arm actuating mechanism, or if the operator should interrupt the wrapping sequence, or if the time base of the controller should momentarily fail. The "heavy loading" of the twine arm actuating mechanism may result in cumulative error over several wrapping sequences but may be overcome by programming the controller to overdrive the twine tube mechanism toward the home, and providing a ratcheting mechanism to disengage the drive when the home position is reached. However, this adds to the cost of the wrapping mechanism and causes additional wear on the drive mechanism.